Adjustable sieves



July 13, 1965 G. TAEGE ADJUSTABLE SIEVES 4 Sheets-Sheet 2 FIGI.4

Filed May 24. 1962 Gunter Toege INVENTOR.

A G E NT.

United States Patent My present invention relates to sieves and, moreparticularly, to riddles and the like provided with an array ofelongated sieve openings.

Sieveswith elongated openings are known in many different forms and havebeen used heretofore for the separation of solids from fluids, for theclassification and separation of solids of different sizes, and asgrates for facilitaing the passage of fluids through solids. In general,such sieves or riddles have comprised a support frame or boxlikestructure, an opening of which was spanned by a generally planar sievesurface provided with perforations to facilitate the passage of liquids,solids and gases while preventing the passage of solids having largerparticle sizes. Frequently, the sieve apparatus comprised means foroscillating the sieve in the plane of its sieve surface or transverselythereto, such means including positive action vibrators entraining thesieve at all times and resonating type vibrators adapted to oscillatethe sieve at its natural frequency against a restoring forceproportional to the mass of the sieve and/or a resilient suspensiontherefor. The present invention relates to riddles of this type.

The sieve surfaces of hitherto existing riddle apparatus have generallybeen formed by a plurality of parallel steel rods orstrips separated bygaps of predetermined gauge. This arrangement had the disadvantage thatthe rods were readily corroded when chemically active material waspassed through the gaps between them. The mechanical characteristics ofthe rods also rendered them unsuitable in may cases since they weresusceptible to metal fatigue and often broke after a relatively shortperiod in use. Attempts to avoid the useof metal rods and to replacethem with rubber threads also were ineffective since such threadsstretched and relaxed non-uniformly so as to affect the size of the gapsformed between them and, consequently, the mesh of the screen. Thedisadvantages of both types of known riddle constructions, especially inthe treatment of comminuted ores, and the preparation of ores forreducing furnaces with the aid of so-called shaking screens oroscillating tables, will be readily apparent. It has also been known toprovide dressing tables for ores and the like with thick rubber platesformed with many small perforations which overlie a heated or unheateddressing plate. This apparatus, although somewhat suitable for thetreatment of floatation slurries in ore classification and'separationprocesses has not found considerable use in the absence of theaforementioned support or dressing plate, since it frequently stretchedinordinately and resulted in an alteration of the gap size. It is anobject of the present invention to provide an improved slotted sieve orriddle adapted to avoid the disadvantages of earlier devices of thischaracter.

A more particular object of the invention is to provide a slotted'sievehaving openings of adjustable width.

These objects are realized according to the invention by the provisionof a riddle with a generally planar sieve surface having through-goingslots, the sieve being formed from elastic material, and a framesurrounding the sieve surface. Advantageously, means are provided totension the sieve against the frame and to stretch itrelatively to theframe thereby selectively adjusting the width of the slots. Theresiliently yieldable sieve may be composed of rubber or any otherelastomer, including any of the "ice known resiliently deformablesynthetic resins. In general, the tensioning means will be effective ina direction transverse to the major dimension of the slots a substantialnumber of which extend codirectionally Within the sieve.

Thus, according to one aspect of the instant invention, a riddlecomprises a frame and a sieve spanning said frame formed integrally froma sheet of elastically deformable material. The sieve is provided withelongated throughgoing slots at least some of which extendcodirectionally and is stretched by a tensioning member in a directiontransverse to these slots. Moreover, the invention contemplatesproviding the sieve with reinforcing elements extending generallyparallel to the codirectional slots. The elongated elements form aparallel array with transverse spacing between which the slots areformed. According to a more particular feature of the invention theslots may have a length onthe order of one or several centimeter and anadjustable width ranging from a fraction of a millimeterup to severalmillimeters, depending upon the degree of tensioning of the sieve. Theelongated elements andthe slots may extend in the longitudinal directionof a generally rectangular sieve or in transverse direction as desired.The invention also contemplates the arraying of slots in lines extendingin their major dimension or in staggered or checkerboard patterns.

According to another aspect of the invention the sieve is composed of aplurality of elongated members joined laterally by webs of elasticallydeformable material which may be stretched to provide the gaps. Thus,the webs may consist of resilient bands of, say, rubber, synthetic resinor other elastomer, which extend transversely of the elongated membersat spaced-apart locations. These tensionable bands are secured to theelongated members so that upon stretchingthe latter spread to form thegaps. Ad-.

vantageously, the elongated members are also provided with tensioningelements (e.g. plasticily deformable steel strips) which extend alongthem remote from the material-processing surface of the sieve.

According to a more particular feature of the invention the reinforcingelements may be wholly or partly embedded in the sieve so as to limitthe possibility of corrosion. If exposed, the elements are preferably ofa corrosion-resistant material, such as stainless steel or Monel metal.The plastic deformability of the elements permits the sieve to be shapedinto substantially any suitable configuraiton, e.g. a surface whereinthe elements extend along generatrices so that formation of filtervessels, sieve troughs, cylinders or the like is possible.

' A riddle according to the invention may be provided with vibratingmeans of a character previously described for reciprocating itpreferably in a direction transverse to the direction alongwhich thereinforcing elements and slotsextend. It has been found that suchreciprocation results'in a self-clearing of the sieve surface so thatthe need for periodic halting of operations is avoided. Fur-- thermore,it is not necessary to remove the sieve in order to release particlesentrapped within the slots inasmuch as a futher tensioning of the sievewill increase the width of the slots to permit any entrapped particlesto fall through. Consequently, a riddle according to the invention isparticularly suitable for use in the separation of liquids, from solidsand theclassification of solids of different. particle sizes. Theaforementioned construction alsofacilitates the bolting of the sieve toits frame.

The above and other objects, features and advantages of the presentinvention will become more readily apparent from the followingdescription, reference being had to the accompanying drawing in which:

FIG. '1 is a plan View of a riddle according to the invention;

embodiment of the invention; 7

- 3 FIG. 2 is a cross-sectional II-II'of FIG.1; i I a FIG. 3 is across-sectional view taken alongthe. line III-III of FIG. 1;

view taken along the line FIGS. 4 and 5. are cross-sectional viewscorresponding;

substantially'to the view of FIG. 2 but showing two modifications o fthe sieve structures in enlarged scale;

FIG. 6 is an enlargedplan view of a portion of the sieve surface showninFIG. 1; V FIGS. 6A, 6B and 6C are views similar to FIG. '6 showingmodified slot arrangements according ,tothe invention; 7 v p a I FIG. 7is a plan view of ,a-riddle according to another FIG. 8 is across-sectional view'taken along thel inje VIII -VIII of FIG. '7;

I n, i V V a that a checkerboard, configuration sis; also'ipossibl e. IIn. FIG. 6A for example, I show the, sieve 3bito be provided 1 withslots 2b extending generally transversely to the direction oftensioning. (arrow 36) offset in a checkerboard pat-1 tern from slots-2])" extendingipai allel;to the direction of tension. Slots 2 b,ofcourse'ext nd parallel tortherein- Iorcing elements I 4b';which aregenerally similar "tenths j elements previollsly describedfi Theelements maybe spanned by resilient reinforcing bandsv37. is desired}It' should be-notedthattensioning of -th e,"sieve 3b ,in jthel,

directionof arrow 3 6will result in a widening (tithe-slots V Zb butinaslight'freductim 1of;;the-.wid'th :ofL slots Zbi.

Another checkerboard configuration is sh'own in FIG; 63V

' FIG. 9 is a cross-sectional view taken along line IX'- 7 IX of FIG;:7;

FIGS. 10-13 are cross-sectional detail views. drawn to enlarged scale,illustrating further embodiments of o my invention;

FIG; 14 is ,a cross-sectional view similar to FIG. 8

showing atensioning device for the sieve;

FIG/15 is a plan view showing a further. tensioning device; and a.FIG.:16 is a perspective view of a trough-shaped sieve according tovthe invention. a In FIG. 1 vI show a riddle which .comprisesa framemember 1 disposed along one edge of a rectangular sieve 3,of elasticallydeformabIemateriaIsuch as rubber, syn-- i is carried byv a supportSleresiliently. mounted on springs: 40which-tend-to return thesievetoaniintermediateposh 1 thetic rubber, plastic or the like. Sieve 3isformedwith through-going slots 2 in the "gaps between. an array oftransversely spaced elongated reinforcing elements 4;- Along thelongitudinal edges of thesieve, resilient'bands 14 are provided spanningthe elements 4. As illustrated,"

sieve 3isintegra1ly formed from a sheet of elastically deformable:material and has its lateral edges 3' lodged in the angle-bar framememberL The sieve 3 isclamped inlthe' frame via bearing strip 7, aclamping plate; 8 and bolts 9 extending perpendicularly to the plane ofthe sieve for urgingithe plate. 8 against, the sieve. The latter isprovided with a material-receiving surface3" overlain' by a'pair ofconventional retaining bars which confine the-material to be processedto a limited region of thesieve 'Aswill be described in greater detailherein after, the='sieve 3 is tensioned via framemember 1 withinsupport31 via bolts .32 and nuts 33." Support 31 is :schematically shownto=be positively reciprocated by a motor and 13'), theelong'atedmember's l2gIwithptheir. sheaths 11g encasing reinforcing' elements'4gt- Ie" lodged rin'ia channeleshaped "resilent, strip jjls jandarebonded theretof v. 'withithe aidof acementitiousmaterial.,jAgaimextensioni of the strip;15inihejdirectionfof arrow 36g resultsrin a,

spreading of the members mg to; definethe slots .2g.- l The) 7 34 viaits eccentric 35.. .Th'elatter arrangement, shown in FIG. 3, oscillatesthe sieve 3-general1y in the direction of arrows 5,-i.e; vin thedirection in which the slots 2 andthe elongated elements 4 extend. v

Strips 14' and the portions of sieve 3 intermediate elements 4constitute stretchable webs which permit the.

selective elongation of sieve 3 via nuts 33 to adjust the widthof'slots2. V Y

As :indicated in FIG. 4the reinforcing, elements 4 may.

be corrosion-resistant strips partly embedded in the sieve; 3 andsecurely bonded thereto, e.g. byvulcanization, with the aid of acementitious substance, or by thermal fusion.

In the arrangement shown in FIG. -5 the strips 4;; conwithinthe sieve 3abetween its row of slots 2d. In this,

wherein slots 2 c: extendparallel to, the elements ,4c while slots 2cextend transv rselythereto. l Nuts z and v2c, v

are grouped within squaresi generally in-accordancerwith av checkerboardpattern. In: "FIG. 6C jtheisieve 3d is shown to be provided with acheckerboard array ofslots, V

2 d extending only parallel :to the reinforcing .elementst tdl In FIGI7Ishowanother riddle-wherein ajsievefiedsi formed by 'apluralityofrparallelelongated membersslzt; bridged by resilient webs 13permittingthe sieve tobe.

tensioned in the. direction ofgarrows 36%.. The members? 12,1havecorresponding upperpsurfaces; substantiallyicon-j tiguousin ;a;relaxedcondition of. the rsievexbutgspaced transversely to define slots'2elupon tensioning of:the, 'sieve.-;

against Vitsframe 10.1 As indicatedin FIG-.1 8 ,I thsieve,v;

tion upon its intermittent dispiacementjnthei directioniof arrow 5byacam,41= Idriven by rnotor 34e. -The reciprocating arrangementconstitutes a non positive .vibrator: for the sieve vwhichoscillates atanaturalfrequency .determined by its masslfgFrom FIG. 10itrnayjbe seenthat elongated members ;121may.,each consist ,ofi a core 42 In amodifiedarrangement of thegriddle (P165112 ceiving surface. of sieve 3g; .7

latter diverge downwardly fawayifrorrrthef material-re J In pFIGL14, Ishowan'arrangement for tensio'ningthe sieve 3e of 'FIG. 7lagainst itsframelflf... The1strips14 are engaged by a.bearingplate;18 whosecorner18'isroundsd,

to prevent tearing of the sieve. 14 in .theldirection of, arrow 36eiagainst: frame member" 1 lllrupon thes'tight ening of itsnut 33e; Themembers '12, of trapezoidal cross-section, are thus spread'todefin'e theslots2e: IniFIG. 15 the tensioningimeans:comprises a bar 45, formingpart of theframe '10:, in which the channel 1510f FIG. 13 isrsecnred."Bar 45Iis displaceable inthe a V stitutingthe 'reinforcingelementsare-wholly embedded case, the strips. 4aneed not 'becorrosion-resistantsince} 7 the sieve material, forming a sheath around them, constitutesanencasing layer of corrosion-resistant material.

,In FIG. 6 I show the slots 2 with greater detail." As."

r illustrated, the extremities of :the slots are provided with;

means, in the formof bores 6, for preventing therupture of sieve 3. atthese extremities upon tensioning of the;

. sieve. Itisjalso possible to provide reinforcing inserts; and to formthe slots;.with angular portions vat these ex-,; tremities inorder toprevent tearing. While the arrange ment shown=in FIGS. 1-6 provides theslots 2 'inrows extending along their major dimensions, it should benoted direction ofarrow36g by a butterfly nutl19 on screw 32g; securedtolthis bar." Arnarm' 46;; rigid with affurther;

frame member 47, serves as a brace. againshwhich-bar efi i and the sieve3g are drawn in the direction 'of arrow 36g.

FIG. 16 shows an arrangement, according to the in'ven L,

tion,whereiu the yieldably deformable bars 4hgarebenta into atrough-configurationandextend along generatricesthereof. The resultingconcave sieve 311' may bestr'etchedg V in the direction oi arrows- 3 6hIto 'vary'the width fit 7 The inventionfas described'and illustrated isbelieved to admit ofQmany. modifications 'within 'the :ability of.

persons'skilled in the art andldeemed to be includedwithin".

the spirit and. scope. of the appended claims; i'f

A bolt 32e'drawsthe' strip- I claim:

1. A riddle comprising a supporting frame; a sieve spanning said frame,said sieve having a planar array of codirectionally extending parallelelongated generally rigid spaced elements forming a plurailty ofelongated throughgoing slots, and resilient means interconnectinglaterally adjacent ones of said elements; and tensioning means includingsaid frame for stretching said resilient means, thereby adjusting thewidths of said slots, said array having a receiving surface for asubstance to be separated, said tensioning means including a tighteningmember for stretching said sieve in a direction generally transverse tothe major dimension of said slots, said resilient means beingconstituted by at least one planar strip of an elastomeric materialinherently elastically stretchable in its plane extending parallel tosaid surface and bonded to said elements.

2. A riddle as defined in claim 1 wherein said elements are resilientlydeformable corrosion-resistant bars.

3. A riddle as defined in claim 1 wherein said elements are metallicbars each encased in a sheath of a corrosionresistant material.

4. A riddle comprising a supporting frame; a sieve spanning said frame,said sieve having a planar array of codirectionally extending parallelelongated generally rigid elements forming a plurality of elongatedthroughgcing slots, and resilient means interconnecting laterallyadjacent ones of said elements; and tensioning means including saidframe for stretching said resilient means, therby adjusting the width ofsaid slots, said array having a receiving surface for a substance to beseparated, said tensioning means including a tightening member forstretching said sieve in a direction generally transverse to the majordimension of said slots, said resilient means including at least twospaced-apart transversely extending deformable bands of elastomericmaterial secured to each of said elements, said tightening member beingadjustable in transverse direction for stretching said bands.

5. A riddle according to claim 4 wherein said elements are oftrapezoidal cross-section and form tapering slots diverging away fromsaid surface.

6. A riddle according to claim 5 wherein said elements havecorresponding faces forming said surface, said faces being substantiallycontiguous laterally in a relaxed condition of said band and definingsaid slots between them in a stretched condition thereof.

References Cited by the Examiner UNITED STATES PATENTS 149,003 3/ 74Tilton 209-394 1,716,758 6/29 Bland 209-392 1,718,385 6/29 Sherwood209-397 1,916,393 6/33 Smith 209-397 2,312,665 3/43 Moore 209-3932,412,905 12/46 Nieuwenhuis 209-397 2,617,600 11/52 Cole 209-3972,740,525 4/56 Wehner 209-399 2,837,210 6/58 Aclrert 209-392 2,893,5607/59 Bixby 209-394 3,018,891 1/62 Bergstrom 209-397 3,134,733 5/64 Rose209-393 FOREIGN PATENTS 19,449 3 05 Austria. 108,053 8/39 Australia.475,428 11/ 37 Great Britain.

HARRY B. THORNTON, Primary Examiner.

HERBERT L. MARTIN, Examiner.

1. A RIDDLE COMPRISING A SUPPORTING FRAME; A SIEVE SPANNING SAD FRAME,SAID SIEVE HAVING A PLANAR ARRAY OF CODIRECTIONALLY EXTENDING PARALLELELONGATED GENERALLY RIGID SPACED ELEMENTS FORMING A PLURALITY OFELONGATED THROUGHGOING SLOTS, AND RESILIENT MEANS INTERCONNECTINGLATERALLY ADJACENT ONES OF SAID ELEMENTS; AND TENSIONING MEANS INCLUDINGSAID FRAME FOR STRETCHING SAID RESILIENT MEANS, THEREBY ADJUSTING THEWIDTHS OF SAID SLOTS, SAID ARRAY HAVING A RECEIVING SURFACE FOR ASUBSTANCE TO BE SEPARATED, SAID TENSIONING MEANS INCLUDING A TIGHTENINGMEMBER FOR STRETCHING SAID SIEVE IN A DIRECTION GENERALLY TRANSVERSE TO